Skywatcher 200p mount question

[rob12770]

Hi, i bought a 2nd hand Skywatcher 200P EQ5 yesterday, i like it but i have a couple of questions,

it came with a long dovetail on the rings, but it also came with what i assume is the original short white mounting  pate, i have put the short on on because i think its much safer due to the locking screw notch and main screw notch.

im wondering why you would need a longer than stock dovetail ? aside from easier balancing i see no advantage.. but being a noob, happy to hear your thoughts..

Also i have a question about the primary mirror, to my surprise it looks like the glass back of the mirror is totally unprotected at the rear of the scope.. isnt this a bit dodgy ?  i would have assumed it would be covered on case it got banged ?

thanks Rob :O)

Edited April 11, 2021 by rob12770
add photos

[rob12770]

anyone ?

[SMF]

Hi Rob,

I have the same scope and really like it. 

It is the long dovetail that came as standard with mine. I’m not sure where the shorter white plate that you have came from. Others might know more. If it’s not tapered in the same way as the dovetail bar then I’d not use it in the manner shown in your picture. It will not be held in the saddle securely enough and the OTA might fall out. That’ll cause a lot of damage.

The rear of the mirror being exposed is normal and most reflectors are like this. You’d really have to be very brutal with it before you could harm it.

Its the inner reflective surface that needs care.

Hope you enjoy it.

Steve

 

[Pixies]

That white plate is a proper Vixen SX dovetail plate, I believe.

[alacant]

Hi

Dovetails. If you're simply looking through it, it doesn't matter which you use.

If you're attaching a camera, to eliminate tube flex, a long wide dovetail, along with a rigid profile to tie the top of the rings is preferred.

To guard against slippage, fix the north end of the dovetail to the ring using a protruding hex head screw.

Place a black shower cap over the main mirror end of the tube to prevent light leak and dust.

HTH

Edited April 11, 2021 by alacant

[Merlin]

There’s an easy solution to making a dovetail bar safe and that’s to file a slot on one side, so that the locking screw is secured in the slot.

[rob12770]

Thanks  very much for your replies guys 👌

a lot  to digest there, i will be using a lightweight..ish  camera lumix GH2

as i say, i feel much safer using the short white dovetail as it has the safety notches, i hear what you say about tube flex, but i will try to file, or modify some notches in the longer rail if i decide to use it..as it is tight now, i fear it could just slide right out if not tight enough..

I plan on motorising the EQ5 mount soon with the  SynScan Pro v3 GOTO Upgrade Kits, so the more stable the better..

Thanks Rob :O)

 

Edited April 12, 2021 by rob12770

[rob12770]

1 hour ago, Merlin said:

There’s an easy solution to making a dovetail bar safe and that’s to file a slot on one side, so that the locking screw is secured in the slot.

i would need a longer locking screw really, but yeah.

[Captain Scarlet]

Part of the point of the exposed glass rear of the mirror is to allow it to radiate heat quickly enough to adjust to temperature changes in good time, as the mirror becomes the wrong shape if different areas of it are at different temperatures.

M

[rob12770]

6 hours ago, Captain Magenta said:

Part of the point of the exposed glass rear of the mirror is to allow it to radiate heat quickly enough to adjust to temperature changes in good time, as the mirror becomes the wrong shape if different areas of it are at different temperatures.

M

Ah, i had wondered if it had something to do with that..i just felt it was rather exposed, with  any other scope i had the mirror  was on a metal mount, i still feel it could be better protected.

Cheers

[rob12770]

9 hours ago, Pixies said:

That white plate is a proper Vixen SX dovetail plate, I believe.

after some googling, although very similar to the Vixen SX, im not sure it is, what i have has little notches cut out for both the main holding screw and the locking screw, the same  as the third one down here.

I notice it says "customer required to drill/tap both mounting plates as necessary) for the secure mounting of your Intes telescope on these precision Sky-Watcher mounts."

looks like my long plate needs drilled / filed as Merlin mentioned earlier 

Cheers

Edited April 12, 2021 by rob12770
more info

[Cosmic Geoff]

I have used several mounts, dovetails and telescopes over the years and have not had any trouble with the dovetail slipping in the clamp.  Unless you point the telescope straight up, the dovetail will tend to jam rather than slip.  On the contrary, with one mount I have had difficulty in releasing the clamp with cold hands at the end of a session.

Some Sky-watcher mount clamps have an extra small screw which is presumably intended as a safety backup.  I suggest that you simply take the usual care in doing up the clamps (and don't undo the wrong one to move the telescope manually in  Dec! 😲)  Note that you will have to move the telescope in the clamp to balance cameras, etc.

[rob12770]

25 minutes ago, Cosmic Geoff said:

 

Some Sky-watcher mount clamps have an extra small screw which is presumably intended as a safety backup

yes, that is what the smaller white clamp is using, it has the notches for it, thats why im using it over the longer dovetail, i feel its much safer..but im new so ..🤷‍♂️

it seems like a really good idea, to me, this is a monster of a telescope so handling it is um..difficult, but im sure il get used to it soon. 

thanks for your input 

[Cosmic Geoff]

3 hours ago, rob12770 said:

I notice it says "customer required to drill/tap both mounting plates as necessary) for the secure mounting of your Intes telescope on these precision Sky-Watcher mounts."

The dovetail bar in your photo is already drilled and tapped. That is the sort of thing they are referring to.

When I had a 203mm f5 Newtonian on an EQ-5, it had a long dovetail bar like that. And it did not slip.

Edited April 12, 2021 by Cosmic Geoff
Addition

[rob12770]

3 minutes ago, Cosmic Geoff said:

The dovetail bar in your photo is already drilled and tapped. That is the sort of thing they are referring to.

if you mean the long black one, no its not, those are just marks made by the screwhead

 

EDIT

wait, i know what you mean now thanks

cheers

Edited April 12, 2021 by rob12770

[alacant]

8" f5 on an eq5 showing rigid tube dovetail arrangement, top bar and anti-slip devices on the underside of the bottom plate.

We found that for astrophotography, anything less requires an OAG.

HTH

[rob12770]

16 minutes ago, alacant said:

8" f5 on an eq5 showing rigid tube dovetail arrangement, top bar and anti-slip devices on the underside of the bottom plate.

We found that for astrophotography, anything less requires an OAG.

HTH

I dont know what an OAG is im afraid ( new to all this )

do  you have any links for the dovetails etc you show here ?

i cant really see the anti slip  locking device

 thanks

[alacant]

Hi

Here is the Dovetail.

Here is the wide clamp which can be attached to your mount via your short dovetail.

The rectangular profile aluminium: from your local window frame guy. We used 60x20mm box section with 2mm walls.

Here is a search on OAG.

There isn't/we've never needed a locking device. Are you able to identify the anti slip arrangement?

HTH

[rob12770]

yes, ok, thats great thanks 👌

[rob12770]

 

Update

After much experimentation, you guys are right, i put the long dovetail  back on, and have tested it, no slipping, i think the main reason im keeping it on ( apart from  tube strength ) is that its a lot easier to get on and off the mount.

thanks again for all your input 👍

Rob